export {}
// 既可以为字符串也可以为数字的数组类型
let arr0: a = [1, 'd']
let arr1: a = [1, 'd']
let arr2: a = [1, 'd']
let arr3: a = [1, 'd']
let arr4: (number | string)[] = [1, 'd']

// 自定义类型、创建类型别名
type a = (number | string)[]
